Today, a co-worker discovered that his contact info for me had been silently updated to overwrite my work e-mail address with my Facebook e-mail address. He discovered this only after sending work e-mails to the wrong address.

And even worse, the e-mails are not actually in my Facebook messages. I checked.

They've vanished into the ether.

For all I know, I could be missing a lot more e-mails from friends, colleagues, or family members, and never even know it.

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As Luxemburg explains, this disaster is happening despite the fact that, like many others, she rushed to replace the @Facebook e-mail with their correct e-mail address once they'd found out about Facebook's change.

When Facebook forced its hundreds of millions of users into an @facebook account, commenters across the Internet talked about alterations that had begun in their contacts and address books outside Facebook -- valid e-mail addresses were being changed for @Facebook without people's awareness or consent on their phones and computers.

I sync my phone with Facebook for many of my contacts. Now I have an address book full of bogus e-mail addresses where they were correct before.

It has now been revealed that automatic altering of users' contacts without notification was, in fact, disturbingly actually built into Apple's new iOS 6 Facebook integration: Facebook for iOS will change address books without any warning.

This is a big deal because everyone who has a mobile device or other software that synchronizes their address book with their FB contacts is in danger of blowing away the perfectly good e-mail address they had for you and replacing it with your FB e-mail address.

[E-mail sent to the @Facebook address] goes to my Facebook in-box, and I don't get a notification e-mail to say it's there. Which is, IMO, even worse -- they don't just pass it through their servers on the way to where it would have gone, they keep it, and fail to send me a copy!

We now also see that the interception of people's e-mail communication with Facebook's new change is deeply problematic and potentially grave.

We've reached out to Facebook for comment and have no response at this time; we'll update this post should new information from Facebook come in.

This is bad news for users that have expectations around e-mail communication by changing their e-mail addresses, intercepting and redirecting their communication elsewhere.

If you have any software or apps that sync your contacts or address books with Facebook (think home computer, devices, phones, iOS 6) check your settings. Now.

Updated 7/1 at 9:40 p.m. PT with Facebook comment blaming user "confusion" for the issue. "By default, messages from friends or friends of friends go into your Inbox," a spokesperson told CNET. "Everything else goes to your Other folder. (If you click on Messages in your left hand navigation menu, you'll see below it an Other folder that drops down.) That is likely where the messages are being sent from other people's emails. Even if that person is friends with them on Facebook, if the friend doesn't have that email on their Facebook account, the message could end up in the Other folder."

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